code: def plot_histograms(ax, prng, nb_samples=10000):
      """Plot 4 histograms and a text annotation."""
      params = ((10, 10), (4, 12), (50, 12), (6, 55))
      for a, b in params:
          values = prng.beta(a, b, size=nb_samples)
          ax.hist(
              values,
              histtype="stepfilled",
              bins=30,
              alpha=0.8,
              density=True,
          )
  
      # Add a small annotation.
      ax.annotate(
          "Annotation",
          xy=(0.25, 4.25),
          xytext=(0.9, 0.9),
          textcoords=ax.transAxes,
          va="top",
          ha="right",
          bbox=dict(boxstyle="round", alpha=0.2),
          arrowprops=dict(
              arrowstyle="->",
              connectionstyle="angle,angleA=-95,angleB=35,rad=10",
          ),
      )
      return ax
  
file_path: matplotlib/galleries/examples/style_sheets/style_sheets_reference.py
imports: import matplotlib.pyplot
  import numpy
  import matplotlib.colors
  from matplotlib.patches import Rectangle
label_desc: Use image node_id 6 for calling a global function with example usage: plot_histograms(ax, prng, nb_samples) and returns: ax